Fire prevention apparatus

ABSTRACT

An apparatus in which an article passageway through a fusing device is closed to prevent a fire originating therein from spreading therefrom. The foregoing abstract is neither intended to define the invention disclosed in the specification, nor is it intended to be limiting as to the scope of the invention in any way.

Elnited States atent 1191 1111' 3,778,222 Suzuki Dec. 11, 1973 [54] FIREPREVENTION APPARATUS 3,603,680 9/1971 Barton 355 3 3,650,616 3/1972Hudson 355 3 [751 WWW: Y Japan 3,650,617 3/1972 Baxter et al. 355/3 I td 3,705,289 12/1972 Szostak et al...... 250/65 ZE [73] AsslgneeCorporamm, S amfor 3,481,590 12/1969 Hovekamp 432/62 [22] Filed: Sept1972 Primary Examiner-John .l. Camby 2 1 App) 290,013 AssistantExaminer-Henry C, Yuen AttorneyJames J. Ralabate et a1.

[52] US. Cl 432/35, 219/216, 432/59,

432/62 [57] ABSTRACT 2 gl An apparatus in which an article passagewaythrough I l 'i"5535; 6 a fusing device is closed to prevent a fireoriginating j 3 therein from spreading therefrom.

6 The foregoing abstract is neither intended to define the inventiondisclosed in the specification, nor is it [56] References Cited intendedto be limiting as to the scope of the invention UNITED STATES PATENTSany 3,697,722 10/1972 Furuichi et al. 219/216 10 Claims, 3 DrawingFigures PATENTEDUEBI 1 I975 SHEET 1 BF 2 FIG. I

FIG. 3

PATENTED DEC! 1 I975 SNEETZBFZ FIRE PREVENTION APPARATUS BACKGROUND OFTHE INVENTION This invention relates generally to electrostatographicprinting, and more particularly concerns an apparatus for preventing thespread of a fire originating in a fusing device used therein.

In electrostatographic printing, an image bearing member is charged to asubstantially uniform level and, thereafter, selectively discharged torecord thereon an electrostatic latent image corresponding to anoriginal document to be reproduced. The latent image is developed orrendered viewable by depositing toner particles thereon. This tonerpowder image may be fused to the image bearing member, or in lieuthereof, transferred to a sheet of final support material and fusedthereto. Generally, the toner particles are a heat settable coloredthermoplastic powder. The toner particles electrostatically adhere tothe image bearing member or final support material, and are passedthrough the fuser which generates heat of sufficient intensity topermanently fix the toner particles in image configuration thereon.

Various types of fusing devices are utilized in electrostatographicprinting. Typical fusing devices utilize radiant heating elements forraising the temperature of the toner material to its set point. However,the temperature within the fusing device must be controlled to insurethat excess heat is not generated therein. If the temperature exceedsthe kindling temperature of the support material, which is typicallyplain paper, a fire may occur therein. This problem is common to mosttypes of fusing devices utilized in electrostatographic printing.l-Ieretofore, a fire produced in the fusing device could rapidly spreadthroughout the remainder of the machine resulting in a great deal ofdamage and requiring extensive repairs. If the burning sheet were notcontained within the machine it is possible for the flaming paper to betransported into the catch tray where it exposes the machine operator toinjury, and the surrounding environment to potential damage.

Accordingly, it is a primary object of the present invention to improvethe fire protection capability of fusing devices used inelectrostatographic printing machines.

SUMMARY OF THE INVENTION Briefly stated and in accordance with thepresent invention, there is provided an apparatus for preventing thespread of a fire originating in a fusing device having an articlepassageway therethrough.

This is accomplished in the present instance by an apparatus includingmeans for sensing the presence of the fire in the fusing device. Whenthe fire is detected, means, responsive to the sensing means, enclosethe passageway through the fusing device. Closing the passageway throughthe fusing device prevents the spread of the fire therefrom.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of thepresent invention will become apparent upon reading the followingdetailed description and upon reference to the drawings, in which:

FIG. 1 is a schematic perspective view of an electrophotographicprinting machine embodying the features of the present invention;

FIG. 2 is an enlarged elevational view of a fusing device having thepresent invention incorporated therein; and

FIG. 3 is an enlarged fragmentary perspective view of a shutter memberused in the present invention.

While the present invention will be described in connection with apreferred embodiment, it will be understood that it is not intended tolimit the invention to that embodiment. On the contrary, it is intendedto cover all alternatives, modifications and equivalents as may beincluded within the spirit and scope of the invention as defined by theappended claims.

DETAILED DESCRIPTION OF THE INVENTION With a continued reference to thedrawings, wherein like reference numerals have been used throughout todesignate like elements, FIG. 1 illustrates an electrophotographicprinting machine for reproducing an original document. Theelectrophotographic printing machine depicted therein employs arotatably mounted drum 10 having a photoconductive surface 12 thereon.Photoconductive surface 12 moves sequentially through a series ofprocessing stations as drum 10 rotates in the direction of arrow 14.

A corona generating device, indicated at 16, is positioned at chargingstation A. Corona generating device 16 extends transversely acrossphotoconductive surface 12 and charges surface 12 to a relatively highuniform potential. A suitable corona generating device is illustrated inU.S. Pat. No. 2,836,725 issued to Vyverberg in 1968.

Charged photoconductive surface 12 is, next, rotated to an exposurestation B. Exposure station B includes a stationary lens system,designated generally at 18, and a scan lamp 20. Original document 22 isplaced face down upon reciprocating platen 24 which moves in a generallyhorizontal plane as indicated by arrow 26. Platen 24 is transparentpermitting scan lamp 20, disposed therebeneath, to illuminateincremental portions of original document 22 as it moves thereover.Light rays reflected from original document 22 irradiate photoconductivesurface 12 to selectively dissipate the charge thereon and record anelectrostatic latent image corresponding to original document 22.

Thereafter, drum 10 is rotated to development station C where theelectrostatic laten image recorded on photoconductive surface 12 isrendered visible. Suitable development apparatus is arranged to deposittoner particles on the electrostatic latent image forming a powder imagethereof. Typical development systems are cascade, magnetic brush orpaddle wheel assemblies. Preferably, the present apparatus includes apaddle wheel arranged to fling the developer material over a guidemember to cascade in a downwardly direction over the photoconductivesurface to develop the latent image.

After development, the powder image electrostatically adheres tophotoconductive surface 12 and advances therewith to transfer station D.Transfer corotron 28, disposed at transfer station D, attracts the tonerpowder image from photoconductive surface 12 to a sheet of final supportmaterial 30. Final support material 30 typically is a suitable plainpaper.

Support material 30 with the powder image thereon is advanced by gripperbars 32 of an endless chain system to fixing station E having fusingdevice 34 positioned therein. Fuser 34 includes radiant heat elements,e.g. infrared lamps, and suitable control circuit means for maintainingthe temperature thereof such that the toner powder image on finalsupport material 30 is permanently adhered thereto. After the powderimage is affixed to support material 30, gripper bars 32 move supportmaterial 30 to a pair of feed out rollers 36 which advance supportmaterial 30 to catch tray 38. In catch tray 38, final support material30 may be readily removed therefrom by a machine operator.

Additional processing stations in the direction of rotation of drum 10,as indicated by arrow 14, are cleaning station F and discharge stationG. Cleaning station F includes a web cleaning system 40 and a pre-cleancorotron 42. Preclean corotron 42 applies a charge potential tophotoconductive surface 12 which loosens or repels residual tonerparticles remaining thereon. This allows web cleaning system 40 toreadily remove the toner particles therefrom. Any residual chargeremaining on photoconductive surface 12 is, thereafter, removed atdischarge station D. Discharge station D directs light rays from scanlamp onto photoconductive surface 12 intermediate web cleaning system 40and corona generating device 16. The light rays dissipate the unwantedbackground potential remaining on photoconductive surface 12.

Each sheet of final support material is advanced by a sheet advancingmechanism utilizing a suitable reverse buckle type of sheet feeder. Thesheet advancing mechanism is indicated generally at 44, and is arrangedto move the sheet of final support material into the gripper bars which,in turn, transport the sheet to the transfer and fusing stations.

Referring now to FIGS. 2 and 3 there is illustrated, in detail, the fireprevention apparatus utilized in fusing device 34 depicted in FIG. 1. Inthe preferred embodiment, fusing device 34 includes an outer housingmember 44 enclosing a pair of heating elements or infrared lamps 46.Gripper bars 32 advance sheet 30 in the direction of arrow 48. Enclosingmeans are provided at both the inlet and outlet of the passagewaythrough the fusing device. The enclosing means includes a shutter member50 mounted rotatably on pin 52 secured to the machine frame. Shuttermember 50 is arranged to be of a length sufficient to close the entireoutlet from the passageway. Side 54 of shutter member 50 is adapted topivot in a downwardly direction so as to enclose the outlet from thepassageway through fusing device 34. Shutter member 50 is maintained inthe open position by an inelastic tension member such as a fusable wire56 having one end thereof attached to shutter member 50 and passingthrough the fusing device and attached to the frame of theelectrostatographic printing machine or, in lieu thereof, to theexternal surface of the fusing device itself. Micro switch 58 engagesside 54 of shutter member 50 being in a closed position when shuttermember 50 is in an open position, i.e. maintaining the passagewaythrough fusing device 34 clear of any impediments. In operation, anyfire within fusing device 34 severs fusible wire 56. After wire 56parts, shutter member 50 pivots in a downwardly direction under theforce of gravity to close the outlet opening of the passageway throughthe fusing device. As the shutter member pivots in the downwardlydirection, side 54 disengages from microswitch 58 and microswitch 58opens. When microswitch 58 is in the open position, the electrostaticprinting machine is nonoperative. In this position, the gripper bars 32can no longer advance the support material thus maintaining the burningsupport material within fusing device 34. In addition, openingofmicroswitch 58 actuates an alarm indicating that there is a fire infusing device 34.

While the present invention has been described such that gravity pivotsshutte member 50 from the open to the closed position, it is'apparentthat any suitable arrangement may be utilized. For example, biasingmeans such as a conventional spring member may be arranged to pivotshutter member 50 from the open to the closed position when a sensingmeans such as the fusible wire indicates the presence of a fire.

With reference to FIGS. 2 and 3, there is shown a shutter member 60arranged to close the inlet to the passageway through fusing device 34.Shutter member 60 is rotatably mounted on pin 64 secured to cover 62.When shutter member 60 rotates under the force of gravity in thedownwardly direction, side end portion 68 engages flat plate 66 securedto the frame of the printing machine thereby closing the inlet to thefuser passageway. Inextensible tension member or fusible wire 70 has oneend thereof secured to projection 72 of shutter member 60. Fusible wire70 extends transversely through fusing device 34 and passes throughslots in members 74, 76 and 78, respectively attached to shutter member60. One end of wire 70 is attached to microswitch 80. When wire 70 issevered by a flame, microswitch 80 is opened. In the open position,microswitch 80 de-energizes the printing machine.

In operation, shutter member 50 functions as a chute leading to papercatch tray 38 (FIG. 1). If the copy paper should start to burn, i.e.,due to a paper jam occurring in fusing device 30 and the fire spreadstoward the outlet side of fusing device 30, the flame cuts fusible wire56. Thereafter, shutter member 50, which is rotatably mounted to thefusing device via pin 52 rotates under the force of gravity such that itcontacts side surface 82 of fusing device 34 and closes the outlet sidethereof. Simultaneously therewith, side 54 of shutter member 50disengages from microswitch 58 causing the de-energization of theprinting machine.

In the event that the fire spreads toward the inlet side of fusingdevice 34, fusible wire 70 extending transversely therethrough in thevicinity of the inlet is flame cut. Thereafter, shutter member 60,rotatably mounted on pin 64 and held in the open position by wire 70,pivots thereabout under the force of gravity until side 68 contacts flatplate 66 closing the inlet side of fusing device 34 to prevent thespread of the fire therefrom. Simultaneously therewith microswitch 80opens so as to de-energize the printing machine.

In recapitulation, the present invention includes sensing means, i.e.fusible wires 56 and 70 arranged to detect the presence of a flamewithin fusing device 34. After the fire is detected, enclosure means,i.e. shutter members 50 and 60 close the outlet and inlet, respectively,to the passageway through fusing device 34 preventing the spread of thefire therefrom.

Thus, it is apparent that there has been provided in accordance withthis invention an apparatus for preventing the spread of a fire from afusing device that satisfies the objects, aims and advantages set forthabove. While this invention has been described in conjunction withspecific embodiments thereof, it is evident that many alternatives,modifications, and variations will be apparent to those skilled in theart in light of the foregoing description. Accordingly, it is intendedto embrace all such alternatives, modifications and variations that fallwithin the spirit and broad scope of the appended claims.

What is claimed is:

1. An apparatus for preventing the spread of a fire originating in afusing device having an article passageway therethrough, including:

means for sensing the presence of the fire in the fusing device; and

means, responsive to said sensing means indicating the fire in thefusing device, for enclosing the passageway through the fusing device toprevent the spread of the fire therefrom.

2. An apparatus as recited in claim 1, further including means for(lo-energizing the fusing device in response to said enclosing meansmoving to a position substantially closing the passageway through thefusing device.

3. An apparatus as recited in claim 1, wherein said enclosing meansincludes shutter members mounted movably on the fusing device andarranged to substantially close the entrance and exit of the passagewaythrough the fusing device in response to said sensing means indicating afire therein.

4. An apparatus for preventing the spread of a fire originating in afusing device having an article passageway therethrough, including:

means for sensing the presence of the fire in the fusing device;

shutter members mounted movably on the fusing device and arranged tosubstantially close the entrance and exit of the passageway through thefusing device in response to said sensing means indicating a firetherein; and

biasing means for resiliently urging said shutter member to move in adirection substantially closing the entrance and exit of the passagewaythrough the fusing device.

5. An apparatus as recited in claim 4, wherein said sensing meansincludes a fusible substantially inextensible tension memberextendingthrough the fusing device and operatively connected at opposite endsthereof to said shutter members and the fusing device, respectively,restraining said shutter members from moving to a position substantiallyclosing the entrance and exit of the passageway through the fusingdevice.

6. An electrostatographic printing machine of the type wherein a tonerpowder image of an original document to be reproduced is formed on asheet of final support material, including:

a housing member having a passageway therethrough;

means for advancing the sheet of support material through the passagewayin said housing member;

means for heating the toner powder image as the sheet of supportmaterial passes through the passageway in said housing member topermanently fix the powder image thereto;

means for sensing the presence of a fire in said housing member; and

means, responsive to said sensing member indicating a fire in saidhousing member, for enclosing the passageway in said housing member toprevent the spread of the fire therefrom.

7. A printing machine as recited in claim 6, further including means forde-energizing the printing machine in response to said enclosing meansmoving to a position substantially closing the passageway through saidhousing member.

8. A printing machine as recited in claim 6, wherein said enclosingmeans includes shutter members mounted movably on said housing memberand arranged to substantially close the entrance and exit of thepassageway through said housing member in response to said sensing meansindicating a fire therein.

9. An electrostatographic printing machine of the type wherein a tonerpowder image of an original document to be reproduced is formed on asheet of final support material, including:

a housing member having a passageway therethrough: means for advancingthe sheet of support material through the passageway in said housingmember;

means for heating the toner powder image as the sheet or supportmaterial passes through the passageway in said housing member topermanently fix the powder image thereto;

means for sensing the presence of a fire in said housing member;

shutter members mounted movably on said housing member and arranged tosubstantially close the entrance and exit of the passageway through saidhousing member in response to said sensing means indicating a firetherein; and

biasing means for resiliently urging said shutter member to move in adirection substantially closing the entrance and exit of the passagewaythrough said housing member.

10. A printing machine as recited in claim 9, wherein said sensing meansincludes fusible substantially inextensible tension members extendingthrough said housing member and operatively connected, at opposed endsthereof, to said shutter members and said housing member, respectively,restraining said shutter members from moving to a position substantiallyclosing the entrance and exit of the passageway through said housingmember.

1. An apparatus for preventing the spread of a fire originating in afusing device having an article passageway therethrough, including:means for sensing the presence of the fire in the fusing device; andmeans, responsive to said sensing means indicating the fire in thefusing device, for enclosing the passageway through the fusing device toprevent the spread of the fire therefrom.
 2. An apparatus as recited inclaim 1, further including means for de-energizing the fusing device inresponse to said enclosing means moving to a position substantiallyclosing the passageway through the fusing device.
 3. An apparatus asrecited in claim 1, wherein said enclosing means includes shuttermembers mounted movably on the fusing device and arranged tosubstantially close the entrance and exit of the passageway through thefusing device in response to said sensing means indicating a firetherein.
 4. An apparatus for preventing the spread of a fire originatingin a fusing device having an article passageway therethrough, including:means for sensing the presence of the fire in the fusing device; shuttermembers mounted movably on the fusing device and arranged tosubstantially close the entrAnce and exit of the passageway through thefusing device in response to said sensing means indicating a firetherein; and biasing means for resiliently urging said shutter member tomove in a direction substantially closing the entrance and exit of thepassageway through the fusing device.
 5. An apparatus as recited inclaim 4, wherein said sensing means includes a fusible substantiallyinextensible tension member extending through the fusing device andoperatively connected at opposite ends thereof to said shutter membersand the fusing device, respectively, restraining said shutter membersfrom moving to a position substantially closing the entrance and exit ofthe passageway through the fusing device.
 6. An electrostatographicprinting machine of the type wherein a toner powder image of an originaldocument to be reproduced is formed on a sheet of final supportmaterial, including: a housing member having a passageway therethrough;means for advancing the sheet of support material through the passagewayin said housing member; means for heating the toner powder image as thesheet of support material passes through the passageway in said housingmember to permanently fix the powder image thereto; means for sensingthe presence of a fire in said housing member; and means, responsive tosaid sensing member indicating a fire in said housing member, forenclosing the passageway in said housing member to prevent the spread ofthe fire therefrom.
 7. A printing machine as recited in claim 6, furtherincluding means for de-energizing the printing machine in response tosaid enclosing means moving to a position substantially closing thepassageway through said housing member.
 8. A printing machine as recitedin claim 6, wherein said enclosing means includes shutter membersmounted movably on said housing member and arranged to substantiallyclose the entrance and exit of the passageway through said housingmember in response to said sensing means indicating a fire therein. 9.An electrostatographic printing machine of the type wherein a tonerpowder image of an original document to be reproduced is formed on asheet of final support material, including: a housing member having apassageway therethrough: means for advancing the sheet of supportmaterial through the passageway in said housing member; means forheating the toner powder image as the sheet or support material passesthrough the passageway in said housing member to permanently fix thepowder image thereto; means for sensing the presence of a fire in saidhousing member; shutter members mounted movably on said housing memberand arranged to substantially close the entrance and exit of thepassageway through said housing member in response to said sensing meansindicating a fire therein; and biasing means for resiliently urging saidshutter member to move in a direction substantially closing the entranceand exit of the passageway through said housing member.
 10. A printingmachine as recited in claim 9, wherein said sensing means includesfusible substantially inextensible tension members extending throughsaid housing member and operatively connected, at opposed ends thereof,to said shutter members and said housing member, respectively,restraining said shutter members from moving to a position substantiallyclosing the entrance and exit of the passageway through said housingmember.